Heat-expandable microspheres, process for producing the same, and application thereof

Abstract

Heat-expandable microspheres include a shell of thermoplastic resin and core material encapsulated in the shell. The core material include a blowing agent having a boiling point not higher than the softening point of the thermoplastic resin and a gas migration inhibitor having a boiling point higher than the softening point of the thermoplastic resin. The ratio of the gas migration inhibitor to the core material is at least 1 weight percent and below 30 weight percent. The average particle size of the heat-expandable microspheres ranges from 1 to 100 micrometers.

1. Heat-expandable microspheres, each comprising a shell of thermoplastic resin and core material encapsulated in the shell and having an average particle size ranging from 1 to 100 micrometer;
 wherein the core material contains a blowing agent having a boiling point not higher than the softening point of the thermoplastic resin and a gas migration inhibitor having a boiling point higher than the softening point of the thermoplastic resin; and 
 wherein the weight ratio of the gas migration inhibitor is at least 1 weight percent and lower than 30 weight percent of the core material. 
 
     
     
       2. Heat-expandable microspheres, each comprising a shell of thermoplastic resin and core material encapsulated in the shell and having an average particle size ranging from 1 to 100 micrometer;
 wherein the core material contains a blowing agent having a boiling point not higher than the softening point of the thermoplastic resin and a gas migration inhibitor having a boiling point higher than the softening point of the thermoplastic resin; and 
 wherein the initial boiling point of the gas migration inhibitor is at least 180 deg.C. 
 
     
     
       3. The heat-expandable microspheres according to  claim 1 , wherein the gas migration inhibitor is at least one member selected from the group consisting of naphthenic oils, paraffinic oils, and aromatic oils. 
     
     
       4. The heat-expandable microspheres according to  claim 2 , wherein the gas migration inhibitor is at least one member selected from the group consisting of naphthenic oils, paraffinic oils, and aromatic oils. 
     
     
       5. Heat-expandable micro spheres, each comprising a shell of thermoplastic resin and core material encapsulated in the shell and having an average particle size ranging from 1 to 100 micrometer;
 wherein the core material essentially contains a blowing agent having a boiling point not higher than the softening point of the thermoplastic resin; and 
 wherein B/A is at least 0.7 in the case that the heat-expandable microspheres having an expansion-initiating temperature Ts (deg.C.) and a maximum expansion ratio A (times) are heated for 10 minutes at T (deg.C.) satisfying the relation of (Ts−15)≦T<Ts and thereafter cooled down to room temperature, and the resultant heat-expandable microspheres have a maximum expansion ratio B (times). 
 
     
     
       6. The heat-expandable microspheres according to  claim 5 , wherein the ratio of the true specific gravity of the heat-expandable microspheres after the heating (d) to the true specific gravity of the heat-expandable microspheres before the heating (d 0 ), which is represented by d/d 0 , ranges from 0.5 to 1.3. 
     
     
       7. The heat-expandable microspheres according to  claim 1 , wherein the thermoplastic resin is produced by polymerizing a polymerizable component, and the polymerizable component contains, as a monomer component, at least one member selected from the group consisting of nitrile monomers, (meth)acrylate monomers, carboxyl-group-containing monomers, styrene monomers, vinyl acetate, (meth)acrylamide monomers, maleimide monomers, and vinylidene chloride. 
     
     
       8. The heat-expandable microspheres according to  claim 2 , wherein the thermoplastic resin is produced by polymerizing a polymerizable component, and the polymerizable component contains, as a monomer component, at least one member selected from the group consisting of nitrile monomers, (meth)acrylate monomers, carboxyl-group-containing monomers, styrene monomers, vinyl acetate, (meth)acrylamide monomers, maleimide monomers, and vinylidene chloride. 
     
     
       9. The heat-expandable microspheres according to  claim 5 , wherein the thermoplastic resin is produced by polymerizing a polymerizable component, and the polymerizable component contains, as a monomer component, at least one member selected from the group consisting of nitrile monomers, (meth)acrylate monomers, carboxyl-group-containing monomers, styrene monomers, vinyl acetate, (meth)acrylamide monomers, maleimide monomers, and vinylidene chloride. 
     
     
       10. The heat-expandable microspheres according to  claim 1 , having a maximum expansion temperature in the range from 120 deg.C. to 240 deg.C. 
     
     
       11. The heat-expandable microspheres according to  claim 2 , having a maximum expansion temperature in the range from 120 deg.C. to 240 deg.C. 
     
     
       12. The heat-expandable microspheres according to  claim 5 , having a maximum expansion temperature in the range from 120 deg.C. to 240 deg.C. 
     
     
       13. The heat-expandable microspheres according to  claim 1 , further comprising a particulate filler being adhered on the outer surface of the shell of the heat-expandable microspheres. 
     
     
       14. The heat-expandable microspheres according to  claim 2 , further comprising a particulate filler being adhered on the outer surface of the shell of the heat-expandable microspheres. 
     
     
       15. The heat-expandable microspheres according to  claim 5 , further comprising a particulate filler being adhered on the outer surface of the shell of the heat-expandable microspheres. 
     
     
       16. Hollow microspheres produced by thermally expanding the heat-expandable microspheres according to  claim 1 . 
     
     
       17. Hollow microspheres produced by thermally expanding the heat-expandable microspheres according to  claim 2 . 
     
     
       18. Hollow microspheres produced by thermally expanding the heat-expandable microspheres according to  claim 5 . 
     
     
       19. A composition comprising a base component except diene rubbers, and the heat-expandable microspheres according to  claim 1 . 
     
     
       20. A composition comprising a base component except diene rubbers, and the heat-expandable microspheres according to  claim 2 . 
     
     
       21. A composition comprising a base component except diene rubbers, and the heat-expandable microspheres according to  claim 5 . 
     
     
       22. A composition comprising a base component except diene rubbers, and the hollow microspheres according to  claim 16 . 
     
     
       23. A composition comprising a base component except diene rubbers, and the hollow microspheres according to  claim 17 . 
     
     
       24. A composition comprising a base component except diene rubbers, and the hollow microspheres according to  claim 18 . 
     
     
       25. A formed product produced by giving a shape to the composition according to  claim 19 . 
     
     
       26. A formed product produced by giving a shape to the composition according to  claim 20 . 
     
     
       27. A formed product produced by giving a shape to the composition according to  claim 21 .